I enjoy Reading this site every night as part of my night time fun. As a professional Tech I can say you never stop learning from others and I have learned so much from you all on this site. My problem is this. I have owned this truck, a 1987 CC Dually 6.9 4.10 LS rear end. I am working toward a full restoration. Today I thought I would do a fluid change to the rear. When I dropped the cover off I noticed some large metal pieces laying in the bottom. Hmmm, what could this be??? Now I have set up many rears over the years and was shocked to realize that those very large pieces were from the pinion gear!! Keep in mind this truck drives great,no gear noise what so ever under acceleration or coast talk about a fluke. I tow a 28ft 17k loaded enclosed car trailer with this thing from time to time!! I can only imagine how lucky I am that nothing bad happened. Everything is tight and the comon loose pinion nut is not the problem and all else is fine. Have any of you ever run into a weakness in our pinion gears? Anyway now I need to find a good set of 4.10s and while it's down maybe rebuild the posi unit since I'm in there now.....Appreciate any thoughts/suggestions inexpensive upgrades you might have.
Sunday Surprise
- Thread starter 1Turbo10
- Start date
LCAM-01XA
Full Access Member
Are you 100% positive the pieces are from the pinion gear that's in there now? If so then holy cow you're a lucky man! Also I agree it's a good time to rebuild the limited slip if it needs it, I tried finding you a clutch kit from Randy's Ring and Pinion site but to no avail. And may I make a selfish request - if you do decide to rebuild the limited slim, when you pull the old clutches and steels out out, can you please not throw them away, but send them my way in the mail? I will pay for shipping and something extra for your trouble, I need the extra clutches for experimenting with my limited slip (basically I'm trying to see how strong-grabbing I can make the factory unit).
david85
Full Access Member
I'd love to see photos of that. I've heard of ring gear bolts backing out or even the odd one missing from factory, but nothing like this. I've seen 4.10s used from time to time. The truth is you might even get a better deal on a complete rear end than buying a brand new set of gears. If you do decide to rebuild what you have, check everything and I do mean everything. I can't help but wonder if the housing might be tweaked a bit. Gears don't chip off for no reason.
Hey LCAM-01XA, At first I thought It was missed on an old fix or at least I was hoping that might be the case as all looked good. You can imagine my surprise when I rolled the carrier around and was looking at almost half of the Pinion gear missing!! It was an OMG Moment!!
Wow, that is pretty strange. What does the ring gear look like? If it was me, I'd check the meshing pattern of what's left (I bet it's ok if it sounds quiet) and if everything else looks good, I'd blame it on a bad pinion. Remember that when it comes to gears if you chip one tooth, it puts that much more load on the surrounding surfaces, not to mention the broken chip can certainly lunch the next tooth/teeth in line.
Just my .02, but I don't tow heavy or far, so it's probably really only .01 worth.
Just my .02, but I don't tow heavy or far, so it's probably really only .01 worth.
As I said, lots of years at this stuff and once in a great while a Drag car would mulch one up. I wouldn't think a two wheel drive N/A 6.9 could even make enough power to break a 10.25 gear set!! 
!! I will need some help with the picture thing, I still use AOL if that tells you anything about my Internet abilities. I will rebuild this bad boy, may cost a little more, but that way It will be all new and I will know what I have. If I get lucky someone here or on Ebay might have a gear set
!! I will need some help with the picture thing, I still use AOL if that tells you anything about my Internet abilities. I will rebuild this bad boy, may cost a little more, but that way It will be all new and I will know what I have. If I get lucky someone here or on Ebay might have a gear setMIDNIGHT RIDER
Full Access Member
- Joined
- Sep 29, 2005
- Posts
- 4,639
- Reaction score
- 38
A friend of mine has been driving around for many years in an old Pontiac station-wagon that is missing several ring-gear teeth; no noise or any other indication of them being gone.
I have known of several cases where a chunk will break out of a few of the teeth, either ring or pinion, most likely due to a flaw in their manufacture.
Usually, rounding the rough edges with a grinder will leave them noise-free for many more years.
I have known of several cases where a chunk will break out of a few of the teeth, either ring or pinion, most likely due to a flaw in their manufacture.
Usually, rounding the rough edges with a grinder will leave them noise-free for many more years.
timothyr1014
Full Access Member
Wow.....all I can say is good find....as in much better than finding that any other way.
Keep in mind when it comes to breaking things like this its more about force than power...you always need a "weak link"...in most race cars the weak link is the tires, on trucks its usually the u-joints. Think about this for a moment...assuming ~300 lbs/ft at the motor and a t19 tranny the rear diff will be seeing close to 1200 lbs/ft of torque, and the rear tires close to 1600 lbs/ft. If you have the rear axle loaded enough to keep from spinning that force has to go somewhere...if she aint moving forward something is gonna break.
I am not saying I think a NA 6.9 could chew a 10.25 ring on demand, but knowing how easily I can overload mine, and looking at the physics that come into play it could get interesting
Keep in mind when it comes to breaking things like this its more about force than power...you always need a "weak link"...in most race cars the weak link is the tires, on trucks its usually the u-joints. Think about this for a moment...assuming ~300 lbs/ft at the motor and a t19 tranny the rear diff will be seeing close to 1200 lbs/ft of torque, and the rear tires close to 1600 lbs/ft. If you have the rear axle loaded enough to keep from spinning that force has to go somewhere...if she aint moving forward something is gonna break.
I am not saying I think a NA 6.9 could chew a 10.25 ring on demand, but knowing how easily I can overload mine, and looking at the physics that come into play it could get interesting
I have not taken it all apart yet, but from looking at the broken parts, I can tell you that there appears to be no rough edges. Everything looks like a smooth rounded break,like a shell in the ocean many years. After getting all your feed back so far I am leaning towards a manufacturing defect that took many years and miles to surface.
What are your thoughts on this. I have a ZF-47 5 speed out of a 96 that I plan on installing, the cool thing is it has the extra low 5.13 or 5- something first gear. I found a set of 3.55 gears I can install but wanted your input. Truck again is a 2 wd Cc Dually and I rarely pull my 28ft enclosed car trailer and would like to be able to use it on the highway more. The T-19 works great but well, you know. I was thinking that extra low first might be the perfect compromise to a 3.55 gear. Your thoughts...
What are your thoughts on this. I have a ZF-47 5 speed out of a 96 that I plan on installing, the cool thing is it has the extra low 5.13 or 5- something first gear. I found a set of 3.55 gears I can install but wanted your input. Truck again is a 2 wd Cc Dually and I rarely pull my 28ft enclosed car trailer and would like to be able to use it on the highway more. The T-19 works great but well, you know. I was thinking that extra low first might be the perfect compromise to a 3.55 gear. Your thoughts...
Last edited:
LCAM-01XA
Full Access Member
Is the '96 ZF out of a diesel truck? You need a diesel trans, a big-block gasoline trans will not bolt up without modifications. But yes, a creeper-gear 5-speed with 3.55s will be really nice combo for both low speed and highway driving...
david85
Full Access Member
Is your truck 2wd or 4wd? the newer tranny won't have a speedo cable drive for your speedometer. If you have a 4wd, then there is no problem because the cable drive will be in the transfer case and that can be reused.
timothyr1014
Full Access Member
Forgive my overthinking, just throwing some food for thought out there.
How heavy are you planning on being on your worst day....and where do you want your saftey net?
as you shift the numbers around you are changing where the torque is multiplied at. keep in mind it is rare to expose things to a full locked load, but from what you are talking about keep this in mind as far as rough numbers assuming 300lb/ft at the crank in first gear you get:
t19 w/4.10's 1206lb/ft on the driveshaft/u-joints, 4945 lb/ft going down the axle and wheels
zf5 (5.13 1st) /3.55's you get 1539 shaft and 5464 axle
while the available 1st gear power gains look impressive keep in mind you have increased your drive shaft u-joint load by almost 28%, but your overall power increase is only 11%.
Personally I like to run a 4.10 or 4.56 rear end, and double overdrives....but then again I am always hauling something, and more often then not it is something heavy
How heavy are you planning on being on your worst day....and where do you want your saftey net?
as you shift the numbers around you are changing where the torque is multiplied at. keep in mind it is rare to expose things to a full locked load, but from what you are talking about keep this in mind as far as rough numbers assuming 300lb/ft at the crank in first gear you get:
t19 w/4.10's 1206lb/ft on the driveshaft/u-joints, 4945 lb/ft going down the axle and wheels
zf5 (5.13 1st) /3.55's you get 1539 shaft and 5464 axle
while the available 1st gear power gains look impressive keep in mind you have increased your drive shaft u-joint load by almost 28%, but your overall power increase is only 11%.
Personally I like to run a 4.10 or 4.56 rear end, and double overdrives....but then again I am always hauling something, and more often then not it is something heavy
sle2115
NRA LIFE MEMBER
I have a set of 4.10's if you want them. I told someone else on here $50 plus shipping. They look very good and have spent a good bit of their time with synthetic gear oil. I switched to 3.73's and used the limited slip from the axle these gears came from. The clutches were perfect and very tight as I was going to rebuild them as well, but after checking things over, decided to leave them as they were. I've had no problems at all with them and believe this axle has been well cared for.
Let me know if your interested, was going to put them on Ebay, but someone on here said they wanted them...haven't heard from them, in a few weeks, so they are yours if you want them.
Let me know if your interested, was going to put them on Ebay, but someone on here said they wanted them...haven't heard from them, in a few weeks, so they are yours if you want them.
